Roll Forming

Roll forming is an important metal forming technology in Australia. The demands for shorter lead times, more complex shapes, new high strength materials and more demanding markets such as the automotive industry, require an improved understanding of the forming process and the increased application of virtual engineering at the design stage.

The main focus of Deakin's Roll Forming Research group are:

Roll forming and flexible roll forming of Ultra High Strength Steels (UHSS) and light weight sheet materials for structural and crash applications in automotive and aerospace.

To understand key process and material parameters and to develop inline process control and shape compensation routines.

Development of new testing routines and material models to improve model accuracy in the Finite Element Analysis (FEA) of roll forming process.

Research Projects

Effect of residual stresses in roll forming process of metal sheets

Recent investigations have shown that residual stress introduced during steel processing may affect the roll forming process and therefore needs to be included in roll forming simulations. Measuring the residual stresses experimentally is expensive, difficult, time consuming, and with limited accuracy.

Previous studies have shown that the presence of residual stress can be analysed by a simple bending test. This work will focus on developing an inverse routine that combined with experimental bend test data allows to estimate residual stress in steel strip (PDF-177kb).

Improvement of the roll forming process by means of the process parameter monitoring

In automotive parts manufacturing, product finish and dimensional accuracy are more important than in conventional roll formed products. Therefore, roll forming to tight tolerances is a new challenge that the industry is facing today. Additionally, due to the high material strength of advanced high strength steel (AHSS) and ultra-high strength steel (UHSS) even small variations in material properties from coil to coil can have a significant effect on product quality. This project will analyse the effect of material parameter changes on forming defects in roll forming with major focus on the development of process monitoring and shape compensation routines (PDF-218kb).

The development of an analytical model to predict web warping in the flexible roll forming of AHSS

To reduce weight and improve passenger safety there is an increased need in the automotive industry to use Ultra High Strength Steels (UHSS) for structural and crash components. However, the application of UHSS is restricted by their limited formability and the difficulty of forming them in conventional processes. An alternative method of manufacturing structural auto body parts from UHSS is the flexible roll forming process which can accommodate materials with high strength and limited ductility in the production of complex and weight-optimised components. However, one major concern in the flexible roll forming is web-warping, which is the height deviation of the profile web area. This project is aiming to gain deep understanding of the effects of material, geometrical and process parameters on web-warping, which may lead to possible parameter control methods for reducing web-warping. Furthermore, based on the analysis, develop an analytical model in order to predict web-warping defect in flexible roll forming (PDF-204kb).

The roll forming of magnesium sheet for automotive applications

In the automotive industry, light weight magnesium alloys are used for die cast components such as gearbox housings, steering wheels and seat frames. However, the majority of the car body consists of steel sheet formed parts which contribute to 25% of the total vehicle weight. Recently there has been increasing interest in using magnesium sheet components to further reduce vehicle weight to make them more fuel efficient.

The forming of magnesium sheet is difficult due to the hexagonal close-packed (HCP) crystal structure of magnesium resulting in high material anisotropy and reduced formability. The issue of limited formability in sheet materials may be overcome by using roll forming, an existing technology that allows the forming of materials that show limited ductility and enables the selective heating of critical forming zones with relatively simple procedures. Roll forming is therefore a promising process for the forming of magnesium sheet components. The major deformation mode in roll forming is bending and so the bending behaviour of magnesium needs to be well understood (PDF-193kb).

The formation of novel structures from ultra-high strength and nano-structured sheet metals through roll forming

Light metals show lower strength compared to steel and this generally requires their use in higher gauges to meet the strength and rigidity requirements of in automotive components.

Recent studies have shown that by refining the microstructure material strength of light metals can be enhanced. This is generally accompanied by a significant loss in formability which precludes the forming with conventional methods such as stamping. Recent investigation suggest that due to their high local ductility nano-structured metals may be roll formable to simple structural sections (PDF-119kb).

Microstructure effects on the forming characteristics of multi phase steel

Low-carbon multiphase steels have been frequently used in applications that require a good combination of strength and ductility, such as body structures in the automotive industry. Dual phase (DP) steels were developed with a high volume fraction of ferrite to ensure a relatively low yield point and good work hardening rates at low strains, as well as regions of martensite to increase tensile strength. They have been extensively utilised in the automotive industry due to their good room-temperature formability and crash performance. Currently there is a significant effort to develop novel materials with light weight and higher strength. One way to achieve this goal is to change the existing microstructure. To be able to adjust the microstructure towards desired material parameters, the effect of the microstructure on forming behaviour must be understood.